A cross sectional study of psychotropic medicine use in Australia in 2018: A focus on polypharmacy

To examine prescribed psychotropic medicine use on a given day in Australia (25 September 2018; World Pharmacists Day), with a focus on psychotropic polypharmacy.

We used a 10% sample of individual-level nationwide dispensing claims to examine psychotropic medicine use on a given day. We estimated the prevalence of psychotropic medicine use in all ages stratified by age and sex. We also calculated the observed vs expected (had medicines been randomly combined) prevalence of psychotropic combinations used. We focused on combinations of clinical significance as well combinations of psychotropics with medicines prescribed to manage cardiovascular risk and disease.

Serotonin reuptake inhibitors, serotonin-noradrenalin reuptake inhibitors/noradrenaline reuptake inhibitors, tricyclic antidepressants and gabapentinoids dominated psychotropic use. The use of any psychotropic as a proportion of people in the Australian population increased with age, peaking at the 85-89 year age group and declining thereafter. Combinations of medicines from the same subclass generally occurred at lower than expected frequencies. However, combinations including atypical antipsychotics occurred more frequently than expected; e.g. 7.4× with anticonvulsants and 2.2× with other atypical antipsychotics. This was also the case for combinations of sedatives, e.g. anxiolytic with hypnotic benzodiazepines (3.8×). Lipid-lowering drugs and antidiabetic medicines were combined with psychotropics at frequencies close to those expected had they been randomly combined.

Psychotropic use in older adults and certain psychotropic combinations that are not well supported with evidence remain prevalent and greater consideration of the drivers of this potentially inappropriate prescribing is required.